The K7RA Solar Update
Tad Cook, K7RA, in Seattle, Washington, reports: Last Thursday, July 17, there were no sunspots at all, a sobering reminder of how weak this solar cycle is. We have to go way back to August 14, 2011, to find the last “spotless” day; the Sun exhibited no spots on January 27, 2011, as well.
On July 18 two new sunspot regions emerged, but the sunspot number was only 26. Two days later, on Sunday, July 20, the sunspot number was just 17, and another new sunspot group emerged. On Tuesday, July 22, two new sunspot regions appeared with a sunspot number of 40, and the next day, July 23, the sunspot number was 55 and another new one emerged.
Solar flux ranged from a low of 86.1 on July 19 to a high of 99.1 on July 23. Outside of those 7 days, the solar flux was 104 on July 24, and the sunspot number remained at 55.
Average daily sunspot numbers from July 17-23 were only 25.9, down from 96.9 in the previous 7-day period. Average daily solar flux dropped nearly 41 points to 90.3.
Predicted solar flux for the near term is 110, 115, and 125 on July 25-27, 140, 155, and 170 on July 28-30, then 185, 170, and 155 on July 31 through August 2, 150 on August 3-5, then 145, 140, 135, and 125 on August 6-9, 120, 115 and 110 on August 10-12, 105 on August 13-14, dropping to 85 on August 18, and rising to 150 on August 29.
Planetary A index was quiet over the past week, and is predicted at 8 on July 25-26, 5 on July 27-28, 12 and 10 on July 29-30, 5 on July 31 through August 4, 8 on August 5-6, 5 on August 7-9, 8 on August 10-11, then 5 on August 12-16, 8 on August 17-18, 5 on August 19-20, then 10 and 8 on August 21-22.
F.K. Janda, OK1HH, says to expect mostly quiet geomagnetic conditions for July 25-26, quiet to unsettled on July 27, quiet on July 28, quiet to unsettled on July 29, quiet for July 30-31, quiet to unsettled on August 1, quiet on August 2, quiet to active on August 3, quiet to unsettled for August 4-7, quiet on August 8, quiet to active on August 9, active to disturbed on August 10, quiet to active August 11, quiet for August 12-15, mostly quiet on August 16, quiet to unsettled on August 17, mostly quiet on August 18, quiet on August 19, quiet to active on August 20, and active to disturbed on August 21.
We received a lot of comments this week asking where the sunspots have gone. The Los Angeles Times ran a piece, “Suddenly, the sun is eerily quiet: Where did the sunspots go?” No sunspots? Sky and Telescope recommends observing faculae. (Thanks to W9WS and TI3/W7RI)
Southgate Amateur Radio Club has posted a video with recordings of aurora communications on 2 meters in Europe 10 years ago today, July 25, 2004.
Ray Soifer, W2RS, of Green Valley, Arizona, continued comments from last week about 6 meter propagation: “Chordal hop Es seems as plausible an explanation as any for my July 5 SSB QSO with EA8DBM,” he reports, “but there's a second chapter to this tale: My CW QSO the following day, at 1447Z. Two such openings on successive days? Maybe that's why it's the ‘Magic Band.’ Magicians don't reveal their tricks.
“Most people who don't live out here (DM41) don't realize how rare transatlantic propagation is for us this far southwest in the absence of F2. In 5 years on the band from this QTH, I've heard (and worked) only two such stations beyond the Caribbean: CU2JT on June 24, 2010, and these two QSOs with Alex. I have worked 47 states (all but DE, AK and HI) on CW and/or SSB, but Europe doesn't come easy.”
TI3/W7RI offered some comments about propagation in Costa Rica: “Here in the lower latitudes, we're seeing the expected downward trend in propagation due to the current sunspot lull,” he said. “Propagation on 10 meters has been spotty at best — typical of what is normally seen at a solar minimum, and the daily 15 meter openings have been starting later in the morning, the mid-day break lasting longer, and the band closing earlier in the evening.
“Even 20 meters has been rather Spartan, and closing completely a few hours after sunset on some days — normally, it's open around the clock here. Not a huge surprise, given that the 304a index is the lowest I have seen it since the last solar minimum, and occasionally even lower than it was during much of that time.
“Six meters hasn't seen a single opening from here in Costa Rica into the States in over a month, just the occasional, brief opening into the Leeward Islands from time to time, sometimes just after sunrise — probably Es. Europe, from here in Central America, remains a dream for this season; nothing so far. Usually, we've had several good openings by this part of the season, but not this year.”
And Pete Corp, K2ARM, also reported on 6 meters on July 23: “Propagation finally came through for my area in the Northeast. I worked three more countries plus more stations in other countries I have worked before. The 6 meter CW portion was all signals from Europe, great operators. It sure looked like F2, but it had to be E2.”
On July 21 Pete wrote, “Tad, that was very good information on the cycles and the days with no sun spots, and even though the HF bands are poor now and the SFI is only 89, 6 meters opened to Europe this morning, and even I worked 2 new countries. It seems like E skip during the summer can happen most anytime, and my records for the last 3 years show good openings every 5 or 6 days. Today I could copy 10 or more Europeans but could only work the two.”
For more information concerning radio propagation, visit the ARRL Technical Information Service page. Also, see the article, “What the Numbers Mean, and Propagation Predictions — a brief introduction to propagation and the major factors affecting it,” by Carl Luetzelschwab, K9LA, for an explanation of the numbers used in this bulletin. An archive of past propagation bulletins also is on the ARRL website, along with monthly propagation charts between four US regions and 12 overseas locations. Carl’s website offers more good information and tutorials about propagation.
Visit the ARRL bulletins page for instructions for starting or ending e-mail distribution of ARRL bulletins.
Sunspot numbers for July 17 through 23 were 0, 26, 27, 17, 16, 40, and 55, with a mean of 25.9. The 10.7 centimeter flux was 88.6, 88.5, 86.1, 87.1, 90.1, 92.6, and 99.1, with a mean of 90.3. Estimated planetary A indices were 5, 3, 3, 3, 5, 5, and 6, with a mean of 4.3. Estimated mid-latitude A indices were 6, 4, 3, 4, 5, 6, and 7, with a mean of 5.